1. Field of the Invention
The invention relates to a processing system, and more particularly to a power control device of a processing system.
2. Description of the Related Art
In general, an electronic system is coupled to an external AC power source. A power management unit in the electronic system converts an AC voltage provided by the external AC power source to operation voltages required for units in the electronic system. During a test process before an electronic system leaves the factory or during usage of the electronic system after it leaves the factory, power provided by an external power source coupled to the electronic system could be not stable. The unstable power may cause the electronic system to be at an unknown state and crash. In detail, when an external AC power source stops providing an AC voltage to an electronic system, a processing unit of the electronic system stores system state data (including system parameters, power information etc.) into a memory and then performs a reset operation. After, the processing unit notifies a power management unit to stop providing an operation voltage to the processing unit. When the external AC power source starts providing the AC voltage again before the processing unit finishes the data storage or the reset operation, the power management unit can not re-provide the operation voltage, so that the electronic system can not recovery to a normal operation mode. Then, the electronic system is at an unknown state and crashes.